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9th Grade Chapter 4 Lesson 2

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For Student Use Only

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9th Grade Chapter 4 Lesson 2

  1. 1. 9 th Grade Chapter 4 Lesson 2 Pgs. 92-96 For Student Use Only
  2. 2. Ocean Currents <ul><li>Countercurrents: </li></ul><ul><ul><li>When surface currents flow other places water from other places rushes in to meet the currents. </li></ul></ul><ul><ul><li>Countercurrent- the current filling the void when surface water moves away. </li></ul></ul><ul><ul><ul><li>Countercurrents can exist on the surface or in a subsurface area </li></ul></ul></ul>
  3. 3. Ocean Currents <ul><li>http://www.dorlingkindersley-uk.co.uk/nf/ClipArt/Thumbnail/0,,239020,00.html </li></ul>
  4. 4. Ocean Currents <ul><li>Waves and Related Phenomena </li></ul><ul><ul><li>Waves: Rhythmic movement of water back and forth that transfer energy </li></ul></ul><ul><ul><ul><li>Wave Parts </li></ul></ul></ul><ul><ul><ul><ul><li>Crest- high point </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Trough- low point </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Period- time between waves </li></ul></ul></ul></ul>
  5. 5. Ocean Currents <ul><li>Wave Formation: </li></ul><ul><ul><li>Three main factors determine the size of these waves: </li></ul></ul><ul><ul><ul><li>Speed of the wind </li></ul></ul></ul><ul><ul><ul><li>The length of time wind blows </li></ul></ul></ul><ul><ul><ul><li>The expanse of open water over which the wind blows </li></ul></ul></ul>
  6. 6. Ocean Currents <ul><li>Waves: </li></ul><ul><ul><li>Choppy- gusty winds cause waves that are different sizes in different sizes and directions </li></ul></ul><ul><ul><li>White Caps: strong winds that whip waves into a spray with a foamy crest </li></ul></ul><ul><ul><li>Ocean Swells: gentle rolling waves </li></ul></ul>
  7. 7. Ocean Currents <ul><li>Wave Motion </li></ul><ul><ul><li>Water only moves a few feet, energy moves to shore </li></ul></ul><ul><ul><ul><li>Breaker: Water moves quicker at top and slower at bottom when water is shallow, the then topples over itself </li></ul></ul></ul><ul><ul><ul><li>Surf: Foaming water that goes up the beach </li></ul></ul></ul>
  8. 8. Ocean Currents <ul><li>Currents: </li></ul><ul><ul><li>Undertow- Small stream of water that is going from shore back to sea </li></ul></ul><ul><ul><li>Longshore current- When there is a sandbar and water that flows parallel to the beach </li></ul></ul><ul><ul><li>Rip Current (Rip Tide)- surface current that carries large amounts of water back to sea through incoming breakers </li></ul></ul>
  9. 9. Ocean Currents <ul><li>Waves: </li></ul><ul><ul><li>Tsunamis- gigantic waves that are caused by earthquakes, volcanic explosion, or undersea landslides. </li></ul></ul><ul><ul><li>These waves can be 200 ft. tall as they build up closer to shore. </li></ul></ul>
  10. 10. Ocean Currents <ul><li>Tides: </li></ul><ul><ul><li>Predictable currents </li></ul></ul><ul><ul><li>Caused by the moon’s gravity </li></ul></ul><ul><ul><ul><li>High Tide- moon’s gravity is strongest </li></ul></ul></ul><ul><ul><ul><li>Low Tide- side not experiencing moon’s gravity </li></ul></ul></ul><ul><ul><ul><li>Spring Tide- sun and moon team up to pull the water </li></ul></ul></ul><ul><ul><ul><li>Neap Tide- weak tides- moon and sun at 90 degree angles </li></ul></ul></ul>

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